During beverage bottling in containers, such as for example glass or plastic bottles, it may be necessary to inspect the filled and sealed containers for the presence of foreign bodies. Here, it is particularly difficult to detect small particles such as transparent glass splinters. Since the containers often have scuff marks or scratches on the bottom, glass splinters can often not be clearly identified.
With regard to this problem it is known from WO 2004/053471 A1 that the content in the bottle can be set into motion on a first carousel by rotation followed by rapid retardation of the bottle and a dark field image of the bottle bottom is obtained from below while the bottle content is still in motion. The foreign bodies, which appear brightly in the image, can be acquired by stationary cameras or cameras which rotate with the bottle. Although devices of this nature can also detect small particles reliably, they are however very complex and space-consuming. In addition, they are only suitable for rotationally symmetrical bottles.
In order to avoid the outlay in terms of apparatus and time for the rotation and retardation of the bottles to be inspected, DE 10 2004 051 961 A1 suggests that the bottle content is set into motion by a vibration device. However, this device is also designed as a rotary machine with infeed and discharge stars. Additionally, a camera is needed for each bottle position on the carousel.
WO 02/01207 A1 describes an inspection device conceived for a straight-line configuration which rotates the containers in a belt station and then guides them past a row of cameras positioned at the side. These cameras supply triggered single images which are compared in an evaluation unit. However, it is difficult to quickly accelerate the bottles and retard them again and to guide them precisely in the belt station, which means that foreign matter cannot be detected with sufficient reliability and accuracy.